Interactions of apolipoprotein E genotype, total cholesterol level, age, and sex in prediction of Alzheimer's disease: a case-control study.

OBJECTIVE

The joint effects of total cholesterol (TC) levels and the APOE genotype in Alzheimer's disease (AD) were evaluated because of previous reports that the APOE locus epsilon 4 allele was associated with both late-onset AD and elevated TC.

DESIGN

Logistic regression was used to determine the effects of the APOE genotype, TC, age, and sex on prediction of AD in a community-based study of 206 cases and 276 controls.

RESULTS

The relationship of the APOE genotype and AD was dependent on TC, age, and sex. However, current TC level does not fully explain the epsilon 4-Alzheimer's disease association. Affected men with higher TC and age under 80 years had the highest epsilon 4 allele frequencies. The epsilon 4 frequency declined significantly with age.

SIGNIFICANCE: A pathologic role of higher TC or cholesterol-based differential survival of epsilon 4-carrying individuals may be involved in the relationship of the epsilon 4 allele with AD. The observed association of the APOE genotype and AD is expected to depend on the age, sex, and TC distributions of a given sample.